The present invention relates to an apparatus for forming stacks of flat objects, such as printed products.
An apparatus of this type is disclosed in CH-A-567 996 and CH-A-609 306. A stack compartment which can be loaded at the top is closed at the bottom by a stack support. After each bundle has been supplied, the stack compartment together with the stack support is rotated through 180°. The stack compartment is assigned driver arrangements which can be driven in a reciprocating manner in order to push a finished stack away from the stack support.
Another apparatus for forming stacks is disclosed by EP-A-0 586 802 and the corresponding U.S. Pat. No. 5,370,382. Two stack-forming devices arranged beside each other are alternately supplied by means of a gripper conveyor with printed products to be stacked. Underneath a pre-stacking space, each stack-forming device has a compartment whose compartment space is bounded on two mutually opposite sides by guide strips. A compartment base which can be raised and lowered is in each case raised in order to pick up a part stack formed in the pre-stacking space, and then lowered again until the objects arranged on it are arranged below slide plates bounding the pre-stacking space. The compartment base, together with the guide strips, can be rotated through 180° in each case in order to form a finished stack, in which the part stacks are in each case arranged lying on one another offset through 180°. As a result, objects such as folded printed products which have a greater thickness in one edge region than at the opposite edge region can be stacked to form stable stacks. In order to eject a finished stack from the compartment, the compartment base is lowered completely and an ejector is moved into the compartment in the ejection direction.
It is an object of the present invention to provide an apparatus of the described type which ensures the formation of stable stacks with short cycle times under all circumstances.